Siemens siprotec 7SA522 User Manual

2.20 Function control and circuit breaker testing
337
7SA522 Manual
C53000-G1176-C155-3
Single-pole Dead
Time
During a single-pole dead time, the load current flowing in the two healthy phases
forces a current flow via earth which may cause undesired pickup. The temporarily ap-
plying zero-sequence voltage may also prompt undesired responses of the protection
functions.
The messages ´SROHRSHQ/µ (FNo. 591), ´SROHRSHQ/µ (FNo. 592) and
´SROHRSHQ/µ (FNo. 593) are generated in addition if the “Open Pole Detector”
recognizes that current and voltage are absent in one phase – but neither in the other
phases current is flowing. In this case, the message will be held up only for as long as
the condition is fulfilled. This enables a single-pole automatic reclosure to be detected
on an unloaded line.
2.20.1.4 Pickup Logic for the Entire Device
Phase Segregated
Fault Detection
The fault detection logic combines the fault detection (pick-up) signals of all protection
functions. In the case of those protection functions that allow for phase segregated
pick-up, the pick-up is output in a phase segregated manner. If a protection function
detects an earth fault, this is also output as a common device alarm. Thus the alarms
´5HOD\3,&.83/µ, ´5HOD\3,&.83/µ, ´5HOD\3,&.83/µ and ´5HOD\
3,&.83(µ are available.
The annunciations above can be allocated to LEDs or output relays. For the local
display of fault event messages and for the transmission of event messages to a per-
sonal computer or a centralized control system, several protection functions provide
the faulted phase information in a single message, e.g. ´'LV3LFNXS/(µ for the
distance protection fault detection in L1–L2–E only one such message appears. It rep-
resents the complete definition of the fault detection.
General Pickup The pickup signals are combined with OR and lead to a general pickup of the device.
It is signaled with the alarm ´5HOD\3,&.83µ. If no protection function of the device
has picked up any longer, ´5HOD\3,&.83µ disappears (message: “OFF”).
General device pickup is a precondition for a series of internal and external functions
that occur subsequently. The following are among the internal functions controlled by
general device pickup:
• Opening of fault case: From general device pickup to general device drop out, all
fault messages are entered in the trip log.
• Initialization of fault storage: The storage and maintenance of fault values can also
be made dependent on the occurrence of a trip command.
• Generation of Spontaneous annunciations: Certain fault messages can be dis-
played as so called spontaneous messages (see “Spontaneous Indications” below).
These display messages can also be made dependent on the general device trip.
• Start action time of automatic reclosure (if available and used)
External functions may be controlled by this indication via an output contact. Examples
are:
• Automatic reclose devices,
• Channel boost in conjunction with signal transmission by PLC,
• Further additional devices or similar.

Siemens siprotec 7SA522 Specifications

General

Brand	Siemens
Model	siprotec 7SA522
Category	Protection Device
Language	English